The invention relates to a control panel for controlling a device in response to a user's input, in particular the invention relates to a control panel having both touch sensitive and mechanical input means.
There is an increasing demand for compact and user friendly control panels for many devices, for example for devices such as portable media players and so forth. These devices are becoming smaller and are being provided with more functionality. To make best use of this increased functionality it is important that the control panel presented to the user (i.e. the user interface) is ergonomic, is simple and intuitive to use, and allows the user to quickly access the functions of the device. There is also a demand for control panels which are both aesthetically pleasing and robust.
It is known for control panels to include both touch sensitive inputs (e.g. capacitive position sensors) and mechanical inputs (e.g. conventional push buttons/switches). For example, the “iPod mini” manufactured by Apple Computer Inc. has a touch sensitive scroll wheel overlaying a number of mechanical switches.
FIG. 1A schematically shows in plan view an example of this kind of control panel. FIG. 1B schematically shows a section view of the control panel shown in FIG. 1A taken along AA′. The control panel 2 is mounted in a wall 4 of a device to be controlled. The control panel includes a capacitive position sensing element 6 in the form of a ring and four conventional mechanical switches. These are coupled to appropriate control circuitry (not shown).
The capacitive position sensing element 6 is formed on a platform printed circuit board (PCB) 10. The platform PCB 10 and the capacitive position sensing element 6 are covered by an outer protective layer 14. The platform PCB 10 is tiltably mounted on a central support 12 so that it can move within an opening in the wall 4 of the device. The support 12 is attached to a base PCB 16. The base PCB 16 and the wall 4 are fixed together. The position of a user's finger touching the sensing element 6 is determined by the control circuitry and may be used to control the device.
The mechanical switches 8 are mounted on the base PCB 16 beneath the capacitive position sensing element 6. By mounting the mechanical switches behind the capacitive position sensing element instead of elsewhere on the device the footprint of the control panel is reduced. Each mechanical switch 8 comprises a deformable diaphragm 8B disposed over a central electrode 8A. Each diaphragm extends away from the base PCB 16 to a height at which it just touches the underside of the platform PCB 10. Switching action is achieved by deforming a selected diaphragm so that it contacts the central electrode 8A. This is done by pressing down on the capacitive position sensing element above the desired switch, This causes the platform PCB 10 to tilt about its central support 12 and compress the diaphragm of the selected switch to bring it into contact with its central electrode.
A user provides instructions through appropriate use of the capacitive position sensing element and the mechanical switches. For example, if the device is a portable music player and the user wishes to play a particular track stored on the device, the user might activate an appropriate one of the mechanical switches to display a listing of the tracks available, then run his finger around the capacitive position sensing element to scroll through the available tracks, and finally press another of the mechanical switches to start playback of the desired track.
Although the control panel 2 shown in FIGS. 1A and 1B provides a compact and intuitive user interface, it has a number of shortcomings. For example, there is a gap 20 between the platform PCB 10 and the wall 4. This means the interior of the device is not sealed. Accordingly, dirt and liquid may enter the device and cause damage. In addition, the mechanical nature of the tilting mechanism is prone to wear and possible eventual failure. Furthermore, because the entire platform PCB 10 is free to tilt about its support, switches can be activated by accident, e.g. by pressing midway between them (which furthermore might activate more than one switch). Accordingly, there is need for a control panel without these shortcomings.